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Calibration jig


S Johnson 2022/01/08 21:17

Does anyone sell or has anyone made a NanoVNA calibration jig, that is a device with the Open/Short/Load standards permanently mounted on a test board with a switch so you can change between them without threading them on/off?

Raj vu2zap 2022/01/09 12:38

The calibration would be off..

At 09/01/2022, you wrote:

Lou W7HV 2022/01/09 04:48

Yeah.  You would be including the impedances and lengths of the connections on said calibration jig in the calibration.  This would likely be OK for HF and probably VHF, where the wavelengths are much longer than the distances on the jig, but it could cause problems in UHF and above.

Lou W7HV 2022/01/09 04:54

I'll add that for using my V2 Plus 4 as an antenna analyzer for HF antennas, I save one 401 point calibration spanning 3MHz to 32MHz and use that one calibration for narrower sweeps within that range.  I find no need to redo that calibration once it's done, so I'm not constantly doing calibrations for every measurement I do.  Similar works for VHF too.

DavidC KD4E 2022/01/09 09:10

This sounds like an excellent idea, probably good for 1.8 - 50MHz,

Using a high quality switch and other quality components, and keeping
leads short and tight, it would simplify many common needs.

For 2m and 220 it may even suffice for close-enough-is-good-enough
measurements of antennas for Field Day, Winter Field Day, POTA, etc.

I know that having to fuss with calibration, in the midst of multiple
distractions, has frequently discouraged me from using mine.

I like the idea ... when you going to start making them?  :-)

David KD4E


> On 1/9/22 12:17 AM, S Johnson wrote:
> Does anyone sell or has anyone made a NanoVNA calibration jig, that > is a device with the Open/Short/Load standards permanently mounted
on > a test board with a switch so you can change between them without >
threading them on/off?

Jim Lux 2022/01/09 09:15

On 1/8/22 9:17 PM, S Johnson wrote:
> Does anyone sell or has anyone made a NanoVNA calibration jig, that is
> a device with the Open/Short/Load standards permanently mounted on a
> test board with a switch so you can change between them without
> threading them on/off?
> _._,_


I've essentially done that with an RCS-8V relay box at the antenna end
of a 100 ft coax run.

Jim Lux 2022/01/09 09:21

On 1/8/22 11:08 PM, Raj vu2zap wrote:
> The calibration would be off..
>
> At 09/01/2022, you wrote:
>> Does anyone sell or has anyone made a NanoVNA calibration jig, that is a device with the Open/Short/Load standards permanently mounted on a test board with a switch so you can change between them without threading them on/off?


This would be like the Keysight/Agilent eCal. What you'd need to do is
tell the VNA the properties of the SOLT through the relays. The vanilla
firmware doesn't have a way to do this, but most of the PC software does
have a way to enter the actual properties of the standard.

The firmware (on both NanoVNA and NanoVNA2) assumes the electrical
length of the standards is zero, when in reality, it isn't (except,
perhaps, the short).

Short, Load, and Open are just the *easiest* mathematically - and
pre-computer days, that was how people did it.  But now, your standards
can be almost anything, as long as they cover a sufficiently large range
of reflection coefficients, and you have the numerical precision to do it.

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